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//===--- SemaCast.cpp - Semantic Analysis for Casts -----------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements semantic analysis for cast expressions, including
// 1) C-style casts like '(int) x'
// 2) C++ functional casts like 'int(x)'
// 3) C++ named casts like 'static_cast<int>(x)'
//
//===----------------------------------------------------------------------===//
#include "clang/Sema/SemaInternal.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/RecordLayout.h"
#include "clang/Basic/PartialDiagnostic.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Sema/Initialization.h"
#include "llvm/ADT/SmallVector.h"
#include <set>
using namespace clang;
enum TryCastResult {
TC_NotApplicable, ///< The cast method is not applicable.
TC_Success, ///< The cast method is appropriate and successful.
TC_Extension, ///< The cast method is appropriate and accepted as a
///< language extension.
TC_Failed ///< The cast method is appropriate, but failed. A
///< diagnostic has been emitted.
};
static bool isValidCast(TryCastResult TCR) {
return TCR == TC_Success || TCR == TC_Extension;
}
enum CastType {
CT_Const, ///< const_cast
CT_Static, ///< static_cast
CT_Reinterpret, ///< reinterpret_cast
CT_Dynamic, ///< dynamic_cast
CT_CStyle, ///< (Type)expr
CT_Functional ///< Type(expr)
};
namespace {
struct CastOperation {
CastOperation(Sema &S, QualType destType, ExprResult src)
: Self(S), SrcExpr(src), DestType(destType),
ResultType(destType.getNonLValueExprType(S.Context)),
ValueKind(Expr::getValueKindForType(destType)),
Kind(CK_Dependent), IsARCUnbridgedCast(false) {
if (const BuiltinType *placeholder =
src.get()->getType()->getAsPlaceholderType()) {
PlaceholderKind = placeholder->getKind();
} else {
PlaceholderKind = (BuiltinType::Kind) 0;
}
}
Sema &Self;
ExprResult SrcExpr;
QualType DestType;
QualType ResultType;
ExprValueKind ValueKind;
CastKind Kind;
BuiltinType::Kind PlaceholderKind;
CXXCastPath BasePath;
bool IsARCUnbridgedCast;
SourceRange OpRange;
SourceRange DestRange;
// Top-level semantics-checking routines.
void CheckConstCast();
void CheckReinterpretCast();
void CheckStaticCast();
void CheckDynamicCast();
void CheckCXXCStyleCast(bool FunctionalCast, bool ListInitialization);
void CheckCStyleCast();
void updatePartOfExplicitCastFlags(CastExpr *CE) {
// Walk down from the CE to the OrigSrcExpr, and mark all immediate
// ImplicitCastExpr's as being part of ExplicitCastExpr. The original CE
// (which is a ExplicitCastExpr), and the OrigSrcExpr are not touched.
for (; auto *ICE = dyn_cast<ImplicitCastExpr>(CE->getSubExpr()); CE = ICE)
ICE->setIsPartOfExplicitCast(true);
}
/// Complete an apparently-successful cast operation that yields
/// the given expression.
ExprResult complete(CastExpr *castExpr) {
// If this is an unbridged cast, wrap the result in an implicit
// cast that yields the unbridged-cast placeholder type.
if (IsARCUnbridgedCast) {
castExpr = ImplicitCastExpr::Create(Self.Context,
Self.Context.ARCUnbridgedCastTy,
CK_Dependent, castExpr, nullptr,
castExpr->getValueKind());
}
updatePartOfExplicitCastFlags(castExpr);
return castExpr;
}
// Internal convenience methods.
/// Try to handle the given placeholder expression kind. Return
/// true if the source expression has the appropriate placeholder
/// kind. A placeholder can only be claimed once.
bool claimPlaceholder(BuiltinType::Kind K) {
if (PlaceholderKind != K) return false;
PlaceholderKind = (BuiltinType::Kind) 0;
return true;
}
bool isPlaceholder() const {
return PlaceholderKind != 0;
}
bool isPlaceholder(BuiltinType::Kind K) const {
return PlaceholderKind == K;
}
// Language specific cast restrictions for address spaces.
void checkAddressSpaceCast(QualType SrcType, QualType DestType);
void checkCastAlign() {
Self.CheckCastAlign(SrcExpr.get(), DestType, OpRange);
}
void checkObjCConversion(Sema::CheckedConversionKind CCK) {
assert(Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers());
Expr *src = SrcExpr.get();
if (Self.CheckObjCConversion(OpRange, DestType, src, CCK) ==
Sema::ACR_unbridged)
IsARCUnbridgedCast = true;
SrcExpr = src;
}
/// Check for and handle non-overload placeholder expressions.
void checkNonOverloadPlaceholders() {
if (!isPlaceholder() || isPlaceholder(BuiltinType::Overload))
return;
SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
if (SrcExpr.isInvalid())
return;
PlaceholderKind = (BuiltinType::Kind) 0;
}
};
}
static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr,
QualType DestType);
// The Try functions attempt a specific way of casting. If they succeed, they
// return TC_Success. If their way of casting is not appropriate for the given
// arguments, they return TC_NotApplicable and *may* set diag to a diagnostic
// to emit if no other way succeeds. If their way of casting is appropriate but
// fails, they return TC_Failed and *must* set diag; they can set it to 0 if
// they emit a specialized diagnostic.
// All diagnostics returned by these functions must expect the same three
// arguments:
// %0: Cast Type (a value from the CastType enumeration)
// %1: Source Type
// %2: Destination Type
static TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr,
QualType DestType, bool CStyle,
CastKind &Kind,
CXXCastPath &BasePath,
unsigned &msg);
static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr,
QualType DestType, bool CStyle,
SourceRange OpRange,
unsigned &msg,
CastKind &Kind,
CXXCastPath &BasePath);
static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType,
QualType DestType, bool CStyle,
SourceRange OpRange,
unsigned &msg,
CastKind &Kind,
CXXCastPath &BasePath);
static TryCastResult TryStaticDowncast(Sema &Self, CanQualType SrcType,
CanQualType DestType, bool CStyle,
SourceRange OpRange,
QualType OrigSrcType,
QualType OrigDestType, unsigned &msg,
CastKind &Kind,
CXXCastPath &BasePath);
static TryCastResult TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr,
QualType SrcType,
QualType DestType,bool CStyle,
SourceRange OpRange,
unsigned &msg,
CastKind &Kind,
CXXCastPath &BasePath);
static TryCastResult TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr,
QualType DestType,
Sema::CheckedConversionKind CCK,
SourceRange OpRange,
unsigned &msg, CastKind &Kind,
bool ListInitialization);
static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr,
QualType DestType,
Sema::CheckedConversionKind CCK,
SourceRange OpRange,
unsigned &msg, CastKind &Kind,
CXXCastPath &BasePath,
bool ListInitialization);
static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr,
QualType DestType, bool CStyle,
unsigned &msg);
static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
QualType DestType, bool CStyle,
SourceRange OpRange,
unsigned &msg,
CastKind &Kind);
/// ActOnCXXNamedCast - Parse {dynamic,static,reinterpret,const}_cast's.
ExprResult
Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
SourceLocation LAngleBracketLoc, Declarator &D,
SourceLocation RAngleBracketLoc,
SourceLocation LParenLoc, Expr *E,
SourceLocation RParenLoc) {
assert(!D.isInvalidType());
TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, E->getType());
if (D.isInvalidType())
return ExprError();
if (getLangOpts().CPlusPlus) {
// Check that there are no default arguments (C++ only).
CheckExtraCXXDefaultArguments(D);
}
return BuildCXXNamedCast(OpLoc, Kind, TInfo, E,
SourceRange(LAngleBracketLoc, RAngleBracketLoc),
SourceRange(LParenLoc, RParenLoc));
}
ExprResult
Sema::BuildCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
TypeSourceInfo *DestTInfo, Expr *E,
SourceRange AngleBrackets, SourceRange Parens) {
ExprResult Ex = E;
QualType DestType = DestTInfo->getType();
// If the type is dependent, we won't do the semantic analysis now.
bool TypeDependent =
DestType->isDependentType() || Ex.get()->isTypeDependent();
CastOperation Op(*this, DestType, E);
Op.OpRange = SourceRange(OpLoc, Parens.getEnd());
Op.DestRange = AngleBrackets;
switch (Kind) {
default: llvm_unreachable("Unknown C++ cast!");
case tok::kw_const_cast:
if (!TypeDependent) {
Op.CheckConstCast();
if (Op.SrcExpr.isInvalid())
return ExprError();
DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
}
return Op.complete(CXXConstCastExpr::Create(Context, Op.ResultType,
Op.ValueKind, Op.SrcExpr.get(), DestTInfo,
OpLoc, Parens.getEnd(),
AngleBrackets));
case tok::kw_dynamic_cast: {
// OpenCL C++ 1.0 s2.9: dynamic_cast is not supported.
if (getLangOpts().OpenCLCPlusPlus) {
return ExprError(Diag(OpLoc, diag::err_openclcxx_not_supported)
<< "dynamic_cast");
}
if (!TypeDependent) {
Op.CheckDynamicCast();
if (Op.SrcExpr.isInvalid())
return ExprError();
}
return Op.complete(CXXDynamicCastExpr::Create(Context, Op.ResultType,
Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
&Op.BasePath, DestTInfo,
OpLoc, Parens.getEnd(),
AngleBrackets));
}
case tok::kw_reinterpret_cast: {
if (!TypeDependent) {
Op.CheckReinterpretCast();
if (Op.SrcExpr.isInvalid())
return ExprError();
DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
}
return Op.complete(CXXReinterpretCastExpr::Create(Context, Op.ResultType,
Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
nullptr, DestTInfo, OpLoc,
Parens.getEnd(),
AngleBrackets));
}
case tok::kw_static_cast: {
if (!TypeDependent) {
Op.CheckStaticCast();
if (Op.SrcExpr.isInvalid())
return ExprError();
DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
}
return Op.complete(CXXStaticCastExpr::Create(Context, Op.ResultType,
Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
&Op.BasePath, DestTInfo,
OpLoc, Parens.getEnd(),
AngleBrackets));
}
}
}
/// Try to diagnose a failed overloaded cast. Returns true if
/// diagnostics were emitted.
static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT,
SourceRange range, Expr *src,
QualType destType,
bool listInitialization) {
switch (CT) {
// These cast kinds don't consider user-defined conversions.
case CT_Const:
case CT_Reinterpret:
case CT_Dynamic:
return false;
// These do.
case CT_Static:
case CT_CStyle:
case CT_Functional:
break;
}
QualType srcType = src->getType();
if (!destType->isRecordType() && !srcType->isRecordType())
return false;
InitializedEntity entity = InitializedEntity::InitializeTemporary(destType);
InitializationKind initKind
= (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(),
range, listInitialization)
: (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range,
listInitialization)
: InitializationKind::CreateCast(/*type range?*/ range);
InitializationSequence sequence(S, entity, initKind, src);
assert(sequence.Failed() && "initialization succeeded on second try?");
switch (sequence.getFailureKind()) {
default: return false;
case InitializationSequence::FK_ConstructorOverloadFailed:
case InitializationSequence::FK_UserConversionOverloadFailed:
break;
}
OverloadCandidateSet &candidates = sequence.getFailedCandidateSet();
unsigned msg = 0;
OverloadCandidateDisplayKind howManyCandidates = OCD_AllCandidates;
switch (sequence.getFailedOverloadResult()) {
case OR_Success: llvm_unreachable("successful failed overload");
case OR_No_Viable_Function:
if (candidates.empty())
msg = diag::err_ovl_no_conversion_in_cast;
else
msg = diag::err_ovl_no_viable_conversion_in_cast;
howManyCandidates = OCD_AllCandidates;
break;
case OR_Ambiguous:
msg = diag::err_ovl_ambiguous_conversion_in_cast;
howManyCandidates = OCD_ViableCandidates;
break;
case OR_Deleted:
msg = diag::err_ovl_deleted_conversion_in_cast;
howManyCandidates = OCD_ViableCandidates;
break;
}
candidates.NoteCandidates(
PartialDiagnosticAt(range.getBegin(),
S.PDiag(msg) << CT << srcType << destType << range
<< src->getSourceRange()),
S, howManyCandidates, src);
return true;
}
/// Diagnose a failed cast.
static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType,
SourceRange opRange, Expr *src, QualType destType,
bool listInitialization) {
if (msg == diag::err_bad_cxx_cast_generic &&
tryDiagnoseOverloadedCast(S, castType, opRange, src, destType,
listInitialization))
return;
S.Diag(opRange.getBegin(), msg) << castType
<< src->getType() << destType << opRange << src->getSourceRange();
// Detect if both types are (ptr to) class, and note any incompleteness.
int DifferentPtrness = 0;
QualType From = destType;
if (auto Ptr = From->getAs<PointerType>()) {
From = Ptr->getPointeeType();
DifferentPtrness++;
}
QualType To = src->getType();
if (auto Ptr = To->getAs<PointerType>()) {
To = Ptr->getPointeeType();
DifferentPtrness--;
}
if (!DifferentPtrness) {
auto RecFrom = From->getAs<RecordType>();
auto RecTo = To->getAs<RecordType>();
if (RecFrom && RecTo) {
auto DeclFrom = RecFrom->getAsCXXRecordDecl();
if (!DeclFrom->isCompleteDefinition())
S.Diag(DeclFrom->getLocation(), diag::note_type_incomplete)
<< DeclFrom->getDeclName();
auto DeclTo = RecTo->getAsCXXRecordDecl();
if (!DeclTo->isCompleteDefinition())
S.Diag(DeclTo->getLocation(), diag::note_type_incomplete)
<< DeclTo->getDeclName();
}
}
}
namespace {
/// The kind of unwrapping we did when determining whether a conversion casts
/// away constness.
enum CastAwayConstnessKind {
/// The conversion does not cast away constness.
CACK_None = 0,
/// We unwrapped similar types.
CACK_Similar = 1,
/// We unwrapped dissimilar types with similar representations (eg, a pointer
/// versus an Objective-C object pointer).
CACK_SimilarKind = 2,
/// We unwrapped representationally-unrelated types, such as a pointer versus
/// a pointer-to-member.
CACK_Incoherent = 3,
};
}
/// Unwrap one level of types for CastsAwayConstness.
///
/// Like Sema::UnwrapSimilarTypes, this removes one level of indirection from
/// both types, provided that they're both pointer-like or array-like. Unlike
/// the Sema function, doesn't care if the unwrapped pieces are related.
///
/// This function may remove additional levels as necessary for correctness:
/// the resulting T1 is unwrapped sufficiently that it is never an array type,
/// so that its qualifiers can be directly compared to those of T2 (which will
/// have the combined set of qualifiers from all indermediate levels of T2),
/// as (effectively) required by [expr.const.cast]p7 replacing T1's qualifiers
/// with those from T2.
static CastAwayConstnessKind
unwrapCastAwayConstnessLevel(ASTContext &Context, QualType &T1, QualType &T2) {
enum { None, Ptr, MemPtr, BlockPtr, Array };
auto Classify = [](QualType T) {
if (T->isAnyPointerType()) return Ptr;
if (T->isMemberPointerType()) return MemPtr;
if (T->isBlockPointerType()) return BlockPtr;
// We somewhat-arbitrarily don't look through VLA types here. This is at
// least consistent with the behavior of UnwrapSimilarTypes.
if (T->isConstantArrayType() || T->isIncompleteArrayType()) return Array;
return None;
};
auto Unwrap = [&](QualType T) {
if (auto *AT = Context.getAsArrayType(T))
return AT->getElementType();
return T->getPointeeType();
};
CastAwayConstnessKind Kind;
if (T2->isReferenceType()) {
// Special case: if the destination type is a reference type, unwrap it as
// the first level. (The source will have been an lvalue expression in this
// case, so there is no corresponding "reference to" in T1 to remove.) This
// simulates removing a "pointer to" from both sides.
T2 = T2->getPointeeType();
Kind = CastAwayConstnessKind::CACK_Similar;
} else if (Context.UnwrapSimilarTypes(T1, T2)) {
Kind = CastAwayConstnessKind::CACK_Similar;
} else {
// Try unwrapping mismatching levels.
int T1Class = Classify(T1);
if (T1Class == None)
return CastAwayConstnessKind::CACK_None;
int T2Class = Classify(T2);
if (T2Class == None)
return CastAwayConstnessKind::CACK_None;
T1 = Unwrap(T1);
T2 = Unwrap(T2);
Kind = T1Class == T2Class ? CastAwayConstnessKind::CACK_SimilarKind
: CastAwayConstnessKind::CACK_Incoherent;
}
// We've unwrapped at least one level. If the resulting T1 is a (possibly
// multidimensional) array type, any qualifier on any matching layer of
// T2 is considered to correspond to T1. Decompose down to the element
// type of T1 so that we can compare properly.
while (true) {
Context.UnwrapSimilarArrayTypes(T1, T2);
if (Classify(T1) != Array)
break;
auto T2Class = Classify(T2);
if (T2Class == None)
break;
if (T2Class != Array)
Kind = CastAwayConstnessKind::CACK_Incoherent;
else if (Kind != CastAwayConstnessKind::CACK_Incoherent)
Kind = CastAwayConstnessKind::CACK_SimilarKind;
T1 = Unwrap(T1);
T2 = Unwrap(T2).withCVRQualifiers(T2.getCVRQualifiers());
}
return Kind;
}
/// Check if the pointer conversion from SrcType to DestType casts away
/// constness as defined in C++ [expr.const.cast]. This is used by the cast
/// checkers. Both arguments must denote pointer (possibly to member) types.
///
/// \param CheckCVR Whether to check for const/volatile/restrict qualifiers.
/// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers.
static CastAwayConstnessKind
CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType,
bool CheckCVR, bool CheckObjCLifetime,
QualType *TheOffendingSrcType = nullptr,
QualType *TheOffendingDestType = nullptr,
Qualifiers *CastAwayQualifiers = nullptr) {
// If the only checking we care about is for Objective-C lifetime qualifiers,
// and we're not in ObjC mode, there's nothing to check.
if (!CheckCVR && CheckObjCLifetime && !Self.Context.getLangOpts().ObjC)
return CastAwayConstnessKind::CACK_None;
if (!DestType->isReferenceType()) {
assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() ||
SrcType->isBlockPointerType()) &&
"Source type is not pointer or pointer to member.");
assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() ||
DestType->isBlockPointerType()) &&
"Destination type is not pointer or pointer to member.");
}
QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType),
UnwrappedDestType = Self.Context.getCanonicalType(DestType);
// Find the qualifiers. We only care about cvr-qualifiers for the
// purpose of this check, because other qualifiers (address spaces,
// Objective-C GC, etc.) are part of the type's identity.
QualType PrevUnwrappedSrcType = UnwrappedSrcType;
QualType PrevUnwrappedDestType = UnwrappedDestType;
auto WorstKind = CastAwayConstnessKind::CACK_Similar;
bool AllConstSoFar = true;
while (auto Kind = unwrapCastAwayConstnessLevel(
Self.Context, UnwrappedSrcType, UnwrappedDestType)) {
// Track the worst kind of unwrap we needed to do before we found a
// problem.
if (Kind > WorstKind)
WorstKind = Kind;
// Determine the relevant qualifiers at this level.
Qualifiers SrcQuals, DestQuals;
Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals);
Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals);
// We do not meaningfully track object const-ness of Objective-C object
// types. Remove const from the source type if either the source or
// the destination is an Objective-C object type.
if (UnwrappedSrcType->isObjCObjectType() ||
UnwrappedDestType->isObjCObjectType())
SrcQuals.removeConst();
if (CheckCVR) {
Qualifiers SrcCvrQuals =
Qualifiers::fromCVRMask(SrcQuals.getCVRQualifiers());
Qualifiers DestCvrQuals =
Qualifiers::fromCVRMask(DestQuals.getCVRQualifiers());
if (SrcCvrQuals != DestCvrQuals) {
if (CastAwayQualifiers)
*CastAwayQualifiers = SrcCvrQuals - DestCvrQuals;
// If we removed a cvr-qualifier, this is casting away 'constness'.
if (!DestCvrQuals.compatiblyIncludes(SrcCvrQuals)) {
if (TheOffendingSrcType)
*TheOffendingSrcType = PrevUnwrappedSrcType;
if (TheOffendingDestType)
*TheOffendingDestType = PrevUnwrappedDestType;
return WorstKind;
}
// If any prior level was not 'const', this is also casting away
// 'constness'. We noted the outermost type missing a 'const' already.
if (!AllConstSoFar)
return WorstKind;
}
}
if (CheckObjCLifetime &&
!DestQuals.compatiblyIncludesObjCLifetime(SrcQuals))
return WorstKind;
// If we found our first non-const-qualified type, this may be the place
// where things start to go wrong.
if (AllConstSoFar && !DestQuals.hasConst()) {
AllConstSoFar = false;
if (TheOffendingSrcType)
*TheOffendingSrcType = PrevUnwrappedSrcType;
if (TheOffendingDestType)
*TheOffendingDestType = PrevUnwrappedDestType;
}
PrevUnwrappedSrcType = UnwrappedSrcType;
PrevUnwrappedDestType = UnwrappedDestType;
}
return CastAwayConstnessKind::CACK_None;
}
static TryCastResult getCastAwayConstnessCastKind(CastAwayConstnessKind CACK,
unsigned &DiagID) {
switch (CACK) {
case CastAwayConstnessKind::CACK_None:
llvm_unreachable("did not cast away constness");
case CastAwayConstnessKind::CACK_Similar:
// FIXME: Accept these as an extension too?
case CastAwayConstnessKind::CACK_SimilarKind:
DiagID = diag::err_bad_cxx_cast_qualifiers_away;
return TC_Failed;
case CastAwayConstnessKind::CACK_Incoherent:
DiagID = diag::ext_bad_cxx_cast_qualifiers_away_incoherent;
return TC_Extension;
}
llvm_unreachable("unexpected cast away constness kind");
}
/// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid.
/// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime-
/// checked downcasts in class hierarchies.
void CastOperation::CheckDynamicCast() {
if (ValueKind == VK_RValue)
SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
else if (isPlaceholder())
SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
return;
QualType OrigSrcType = SrcExpr.get()->getType();
QualType DestType = Self.Context.getCanonicalType(this->DestType);
// C++ 5.2.7p1: T shall be a pointer or reference to a complete class type,
// or "pointer to cv void".
QualType DestPointee;
const PointerType *DestPointer = DestType->getAs<PointerType>();
const ReferenceType *DestReference = nullptr;
if (DestPointer) {
DestPointee = DestPointer->getPointeeType();
} else if ((DestReference = DestType->getAs<ReferenceType>())) {
DestPointee = DestReference->getPointeeType();
} else {
Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr)
<< this->DestType << DestRange;
SrcExpr = ExprError();
return;
}
const RecordType *DestRecord = DestPointee->getAs<RecordType>();
if (DestPointee->isVoidType()) {
assert(DestPointer && "Reference to void is not possible");
} else if (DestRecord) {
if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee,
diag::err_bad_dynamic_cast_incomplete,
DestRange)) {
SrcExpr = ExprError();
return;
}
} else {
Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
<< DestPointee.getUnqualifiedType() << DestRange;
SrcExpr = ExprError();
return;
}
// C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to
// complete class type, [...]. If T is an lvalue reference type, v shall be
// an lvalue of a complete class type, [...]. If T is an rvalue reference
// type, v shall be an expression having a complete class type, [...]
QualType SrcType = Self.Context.getCanonicalType(OrigSrcType);
QualType SrcPointee;
if (DestPointer) {
if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
SrcPointee = SrcPointer->getPointeeType();
} else {
Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr)
<< OrigSrcType << SrcExpr.get()->getSourceRange();
SrcExpr = ExprError();
return;
}
} else if (DestReference->isLValueReferenceType()) {
if (!SrcExpr.get()->isLValue()) {
Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue)
<< CT_Dynamic << OrigSrcType << this->DestType << OpRange;
}
SrcPointee = SrcType;
} else {
// If we're dynamic_casting from a prvalue to an rvalue reference, we need
// to materialize the prvalue before we bind the reference to it.
if (SrcExpr.get()->isRValue())
SrcExpr = Self.CreateMaterializeTemporaryExpr(
SrcType, SrcExpr.get(), /*IsLValueReference*/ false);
SrcPointee = SrcType;
}
const RecordType *SrcRecord = SrcPointee->getAs<RecordType>();
if (SrcRecord) {
if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee,
diag::err_bad_dynamic_cast_incomplete,
SrcExpr.get())) {
SrcExpr = ExprError();
return;
}
} else {
Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
<< SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange();
SrcExpr = ExprError();
return;
}
assert((DestPointer || DestReference) &&
"Bad destination non-ptr/ref slipped through.");
assert((DestRecord || DestPointee->isVoidType()) &&
"Bad destination pointee slipped through.");
assert(SrcRecord && "Bad source pointee slipped through.");
// C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness.
if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) {
Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away)
<< CT_Dynamic << OrigSrcType << this->DestType << OpRange;
SrcExpr = ExprError();
return;
}
// C++ 5.2.7p3: If the type of v is the same as the required result type,
// [except for cv].
if (DestRecord == SrcRecord) {
Kind = CK_NoOp;
return;
}
// C++ 5.2.7p5
// Upcasts are resolved statically.
if (DestRecord &&
Self.IsDerivedFrom(OpRange.getBegin(), SrcPointee, DestPointee)) {
if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee,
OpRange.getBegin(), OpRange,
&BasePath)) {
SrcExpr = ExprError();
return;
}
Kind = CK_DerivedToBase;
return;
}
// C++ 5.2.7p6: Otherwise, v shall be [polymorphic].
const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition();
assert(SrcDecl && "Definition missing");
if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) {
Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic)
<< SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange();
SrcExpr = ExprError();
}
// dynamic_cast is not available with -fno-rtti.
// As an exception, dynamic_cast to void* is available because it doesn't
// use RTTI.
if (!Self.getLangOpts().RTTI && !DestPointee->isVoidType()) {
Self.Diag(OpRange.getBegin(), diag::err_no_dynamic_cast_with_fno_rtti);
SrcExpr = ExprError();
return;
}
// Done. Everything else is run-time checks.
Kind = CK_Dynamic;
}
/// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid.
/// Refer to C++ 5.2.11 for details. const_cast is typically used in code
/// like this:
/// const char *str = "literal";
/// legacy_function(const_cast\<char*\>(str));
void CastOperation::CheckConstCast() {
if (ValueKind == VK_RValue)
SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
else if (isPlaceholder())
SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
return;
unsigned msg = diag::err_bad_cxx_cast_generic;
auto TCR = TryConstCast(Self, SrcExpr, DestType, /*CStyle*/ false, msg);
if (TCR != TC_Success && msg != 0) {
Self.Diag(OpRange.getBegin(), msg) << CT_Const
<< SrcExpr.get()->getType() << DestType << OpRange;
}
if (!isValidCast(TCR))
SrcExpr = ExprError();
}
/// Check that a reinterpret_cast\<DestType\>(SrcExpr) is not used as upcast
/// or downcast between respective pointers or references.
static void DiagnoseReinterpretUpDownCast(Sema &Self, const Expr *SrcExpr,
QualType DestType,
SourceRange OpRange) {
QualType SrcType = SrcExpr->getType();
// When casting from pointer or reference, get pointee type; use original
// type otherwise.
const CXXRecordDecl *SrcPointeeRD = SrcType->getPointeeCXXRecordDecl();
const CXXRecordDecl *SrcRD =
SrcPointeeRD ? SrcPointeeRD : SrcType->getAsCXXRecordDecl();
// Examining subobjects for records is only possible if the complete and
// valid definition is available. Also, template instantiation is not
// allowed here.
if (!SrcRD || !SrcRD->isCompleteDefinition() || SrcRD->isInvalidDecl())
return;
const CXXRecordDecl *DestRD = DestType->getPointeeCXXRecordDecl();
if (!DestRD || !DestRD->isCompleteDefinition() || DestRD->isInvalidDecl())
return;
enum {
ReinterpretUpcast,
ReinterpretDowncast
} ReinterpretKind;
CXXBasePaths BasePaths;
if (SrcRD->isDerivedFrom(DestRD, BasePaths))
ReinterpretKind = ReinterpretUpcast;
else if (DestRD->isDerivedFrom(SrcRD, BasePaths))
ReinterpretKind = ReinterpretDowncast;
else
return;
bool VirtualBase = true;
bool NonZeroOffset = false;
for (CXXBasePaths::const_paths_iterator I = BasePaths.begin(),
E = BasePaths.end();
I != E; ++I) {
const CXXBasePath &Path = *I;
CharUnits Offset = CharUnits::Zero();
bool IsVirtual = false;
for (CXXBasePath::const_iterator IElem = Path.begin(), EElem = Path.end();
IElem != EElem; ++IElem) {
IsVirtual = IElem->Base->isVirtual();
if (IsVirtual)
break;
const CXXRecordDecl *BaseRD = IElem->Base->getType()->getAsCXXRecordDecl();
assert(BaseRD && "Base type should be a valid unqualified class type");
// Don't check if any base has invalid declaration or has no definition
// since it has no layout info.
const CXXRecordDecl *Class = IElem->Class,
*ClassDefinition = Class->getDefinition();
if (Class->isInvalidDecl() || !ClassDefinition ||
!ClassDefinition->isCompleteDefinition())
return;
const ASTRecordLayout &DerivedLayout =
Self.Context.getASTRecordLayout(Class);
Offset += DerivedLayout.getBaseClassOffset(BaseRD);
}
if (!IsVirtual) {
// Don't warn if any path is a non-virtually derived base at offset zero.
if (Offset.isZero())
return;
// Offset makes sense only for non-virtual bases.
else
NonZeroOffset = true;
}
VirtualBase = VirtualBase && IsVirtual;
}
(void) NonZeroOffset; // Silence set but not used warning.
assert((VirtualBase || NonZeroOffset) &&
"Should have returned if has non-virtual base with zero offset");
QualType BaseType =
ReinterpretKind == ReinterpretUpcast? DestType : SrcType;
QualType DerivedType =
ReinterpretKind == ReinterpretUpcast? SrcType : DestType;
SourceLocation BeginLoc = OpRange.getBegin();
Self.Diag(BeginLoc, diag::warn_reinterpret_different_from_static)
<< DerivedType << BaseType << !VirtualBase << int(ReinterpretKind)
<< OpRange;
Self.Diag(BeginLoc, diag::note_reinterpret_updowncast_use_static)
<< int(ReinterpretKind)
<< FixItHint::CreateReplacement(BeginLoc, "static_cast");
}
/// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is
/// valid.
/// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code
/// like this:
/// char *bytes = reinterpret_cast\<char*\>(int_ptr);
void CastOperation::CheckReinterpretCast() {
if (ValueKind == VK_RValue && !isPlaceholder(BuiltinType::Overload))
SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
else
checkNonOverloadPlaceholders();
if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
return;
unsigned msg = diag::err_bad_cxx_cast_generic;
TryCastResult tcr =
TryReinterpretCast(Self, SrcExpr, DestType,
/*CStyle*/false, OpRange, msg, Kind);
if (tcr != TC_Success && msg != 0) {
if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
return;
if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
//FIXME: &f<int>; is overloaded and resolvable
Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload)
<< OverloadExpr::find(SrcExpr.get()).Expression->getName()
<< DestType << OpRange;
Self.NoteAllOverloadCandidates(SrcExpr.get());
} else {
diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(),
DestType, /*listInitialization=*/false);
}
}
if (isValidCast(tcr)) {
if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers())
checkObjCConversion(Sema::CCK_OtherCast);
DiagnoseReinterpretUpDownCast(Self, SrcExpr.get(), DestType, OpRange);
} else {
SrcExpr = ExprError();
}
}
/// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid.
/// Refer to C++ 5.2.9 for details. Static casts are mostly used for making
/// implicit conversions explicit and getting rid of data loss warnings.
void CastOperation::CheckStaticCast() {
if (isPlaceholder()) {
checkNonOverloadPlaceholders();
if (SrcExpr.isInvalid())
return;
}
// This test is outside everything else because it's the only case where
// a non-lvalue-reference target type does not lead to decay.
// C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
if (DestType->isVoidType()) {
Kind = CK_ToVoid;
if (claimPlaceholder(BuiltinType::Overload)) {
Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr,
false, // Decay Function to ptr
true, // Complain
OpRange, DestType, diag::err_bad_static_cast_overload);
if (SrcExpr.isInvalid())
return;
}
SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
return;
}
if (ValueKind == VK_RValue && !DestType->isRecordType() &&
!isPlaceholder(BuiltinType::Overload)) {
SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
return;
}
unsigned msg = diag::err_bad_cxx_cast_generic;
TryCastResult tcr
= TryStaticCast(Self, SrcExpr, DestType, Sema::CCK_OtherCast, OpRange, msg,
Kind, BasePath, /*ListInitialization=*/false);
if (tcr != TC_Success && msg != 0) {
if (SrcExpr.isInvalid())
return;
if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression;
Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload)
<< oe->getName() << DestType << OpRange
<< oe->getQualifierLoc().getSourceRange();
Self.NoteAllOverloadCandidates(SrcExpr.get());
} else {
diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType,
/*listInitialization=*/false);
}
}
if (isValidCast(tcr)) {
if (Kind == CK_BitCast)
checkCastAlign();
if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers())
checkObjCConversion(Sema::CCK_OtherCast);
} else {
SrcExpr = ExprError();
}
}
static bool IsAddressSpaceConversion(QualType SrcType, QualType DestType) {
auto *SrcPtrType = SrcType->getAs<PointerType>();
if (!SrcPtrType)
return false;
auto *DestPtrType = DestType->getAs<PointerType>();
if (!DestPtrType)
return false;
return SrcPtrType->getPointeeType().getAddressSpace() !=
DestPtrType->getPointeeType().getAddressSpace();
}
/// TryStaticCast - Check if a static cast can be performed, and do so if
/// possible. If @p CStyle, ignore access restrictions on hierarchy casting
/// and casting away constness.
static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr,
QualType DestType,
Sema::CheckedConversionKind CCK,
SourceRange OpRange, unsigned &msg,
CastKind &Kind, CXXCastPath &BasePath,
bool ListInitialization) {
// Determine whether we have the semantics of a C-style cast.
bool CStyle
= (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast);
// The order the tests is not entirely arbitrary. There is one conversion
// that can be handled in two different ways. Given:
// struct A {};
// struct B : public A {
// B(); B(const A&);
// };
// const A &a = B();
// the cast static_cast<const B&>(a) could be seen as either a static
// reference downcast, or an explicit invocation of the user-defined
// conversion using B's conversion constructor.
// DR 427 specifies that the downcast is to be applied here.
// C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
// Done outside this function.
TryCastResult tcr;
// C++ 5.2.9p5, reference downcast.
// See the function for details.
// DR 427 specifies that this is to be applied before paragraph 2.
tcr = TryStaticReferenceDowncast(Self, SrcExpr.get(), DestType, CStyle,
OpRange, msg, Kind, BasePath);
if (tcr != TC_NotApplicable)
return tcr;
// C++11 [expr.static.cast]p3:
// A glvalue of type "cv1 T1" can be cast to type "rvalue reference to cv2
// T2" if "cv2 T2" is reference-compatible with "cv1 T1".
tcr = TryLValueToRValueCast(Self, SrcExpr.get(), DestType, CStyle, Kind,
BasePath, msg);
if (tcr != TC_NotApplicable)
return tcr;
// C++ 5.2.9p2: An expression e can be explicitly converted to a type T
// [...] if the declaration "T t(e);" is well-formed, [...].
tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CCK, OpRange, msg,
Kind, ListInitialization);
if (SrcExpr.isInvalid())
return TC_Failed;
if (tcr != TC_NotApplicable)
return tcr;
// C++ 5.2.9p6: May apply the reverse of any standard conversion, except
// lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean
// conversions, subject to further restrictions.
// Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal
// of qualification conversions impossible.
// In the CStyle case, the earlier attempt to const_cast should have taken
// care of reverse qualification conversions.
QualType SrcType = Self.Context.getCanonicalType(SrcExpr.get()->getType());
// C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly
// converted to an integral type. [...] A value of a scoped enumeration type
// can also be explicitly converted to a floating-point type [...].
if (const EnumType *Enum = SrcType->getAs<EnumType>()) {
if (Enum->getDecl()->isScoped()) {
if (DestType->isBooleanType()) {
Kind = CK_IntegralToBoolean;
return TC_Success;
} else if (DestType->isIntegralType(Self.Context)) {
Kind = CK_IntegralCast;
return TC_Success;
} else if (DestType->isRealFloatingType()) {
Kind = CK_IntegralToFloating;
return TC_Success;
}
}
}
// Reverse integral promotion/conversion. All such conversions are themselves
// again integral promotions or conversions and are thus already handled by
// p2 (TryDirectInitialization above).
// (Note: any data loss warnings should be suppressed.)
// The exception is the reverse of enum->integer, i.e. integer->enum (and
// enum->enum). See also C++ 5.2.9p7.
// The same goes for reverse floating point promotion/conversion and
// floating-integral conversions. Again, only floating->enum is relevant.
if (DestType->isEnumeralType()) {
if (SrcType->isIntegralOrEnumerationType()) {
Kind = CK_IntegralCast;
return TC_Success;
} else if (SrcType->isRealFloatingType()) {
Kind = CK_FloatingToIntegral;
return TC_Success;
}
}
// Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast.
// C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance.
tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg,
Kind, BasePath);
if (tcr != TC_NotApplicable)
return tcr;
// Reverse member pointer conversion. C++ 4.11 specifies member pointer
// conversion. C++ 5.2.9p9 has additional information.
// DR54's access restrictions apply here also.
tcr = TryStaticMemberPointerUpcast(Self, SrcExpr, SrcType, DestType, CStyle,
OpRange, msg, Kind, BasePath);
if (tcr != TC_NotApplicable)
return tcr;
// Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to
// void*. C++ 5.2.9p10 specifies additional restrictions, which really is
// just the usual constness stuff.
if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
QualType SrcPointee = SrcPointer->getPointeeType();
if (SrcPointee->isVoidType()) {
if (const PointerType *DestPointer = DestType->getAs<PointerType>()) {
QualType DestPointee = DestPointer->getPointeeType();
if (DestPointee->isIncompleteOrObjectType()) {
// This is definitely the intended conversion, but it might fail due
// to a qualifier violation. Note that we permit Objective-C lifetime
// and GC qualifier mismatches here.
if (!CStyle) {
Qualifiers DestPointeeQuals = DestPointee.getQualifiers();
Qualifiers SrcPointeeQuals = SrcPointee.getQualifiers();
DestPointeeQuals.removeObjCGCAttr();
DestPointeeQuals.removeObjCLifetime();
SrcPointeeQuals.removeObjCGCAttr();
SrcPointeeQuals.removeObjCLifetime();
if (DestPointeeQuals != SrcPointeeQuals &&
!DestPointeeQuals.compatiblyIncludes(SrcPointeeQuals)) {
msg = diag::err_bad_cxx_cast_qualifiers_away;
return TC_Failed;
}
}
Kind = IsAddressSpaceConversion(SrcType, DestType)
? CK_AddressSpaceConversion
: CK_BitCast;
return TC_Success;
}
// Microsoft permits static_cast from 'pointer-to-void' to
// 'pointer-to-function'.
if (!CStyle && Self.getLangOpts().MSVCCompat &&
DestPointee->isFunctionType()) {
Self.Diag(OpRange.getBegin(), diag::ext_ms_cast_fn_obj) << OpRange;
Kind = CK_BitCast;
return TC_Success;
}
}
else if (DestType->isObjCObjectPointerType()) {
// allow both c-style cast and static_cast of objective-c pointers as
// they are pervasive.
Kind = CK_CPointerToObjCPointerCast;
return TC_Success;
}
else if (CStyle && DestType->isBlockPointerType()) {
// allow c-style cast of void * to block pointers.
Kind = CK_AnyPointerToBlockPointerCast;
return TC_Success;
}
}
}
// Allow arbitrary objective-c pointer conversion with static casts.
if (SrcType->isObjCObjectPointerType() &&
DestType->isObjCObjectPointerType()) {
Kind = CK_BitCast;
return TC_Success;
}
// Allow ns-pointer to cf-pointer conversion in either direction
// with static casts.
if (!CStyle &&
Self.CheckTollFreeBridgeStaticCast(DestType, SrcExpr.get(), Kind))
return TC_Success;
// See if it looks like the user is trying to convert between
// related record types, and select a better diagnostic if so.
if (auto SrcPointer = SrcType->getAs<PointerType>())
if (auto DestPointer = DestType->getAs<PointerType>())
if (SrcPointer->getPointeeType()->getAs<RecordType>() &&
DestPointer->getPointeeType()->getAs<RecordType>())
msg = diag::err_bad_cxx_cast_unrelated_class;
// We tried everything. Everything! Nothing works! :-(
return TC_NotApplicable;
}
/// Tests whether a conversion according to N2844 is valid.
TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr,
QualType DestType, bool CStyle,
CastKind &Kind, CXXCastPath &BasePath,
unsigned &msg) {
// C++11 [expr.static.cast]p3:
// A glvalue of type "cv1 T1" can be cast to type "rvalue reference to
// cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1".
const RValueReferenceType *R = DestType->getAs<RValueReferenceType>();
if (!R)
return TC_NotApplicable;
if (!SrcExpr->isGLValue())
return TC_NotApplicable;
// Because we try the reference downcast before this function, from now on
// this is the only cast possibility, so we issue an error if we fail now.
// FIXME: Should allow casting away constness if CStyle.
bool DerivedToBase;
bool ObjCConversion;
bool ObjCLifetimeConversion;
QualType FromType = SrcExpr->getType();
QualType ToType = R->getPointeeType();
if (CStyle) {
FromType = FromType.getUnqualifiedType();
ToType = ToType.getUnqualifiedType();
}
Sema::ReferenceCompareResult RefResult = Self.CompareReferenceRelationship(
SrcExpr->getBeginLoc(), ToType, FromType, DerivedToBase, ObjCConversion,
ObjCLifetimeConversion);
if (RefResult != Sema::Ref_Compatible) {
if (CStyle || RefResult == Sema::Ref_Incompatible)
return TC_NotApplicable;
// Diagnose types which are reference-related but not compatible here since
// we can provide better diagnostics. In these cases forwarding to
// [expr.static.cast]p4 should never result in a well-formed cast.
msg = SrcExpr->isLValue() ? diag::err_bad_lvalue_to_rvalue_cast
: diag::err_bad_rvalue_to_rvalue_cast;
return TC_Failed;
}
if (DerivedToBase) {
Kind = CK_DerivedToBase;
CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
/*DetectVirtual=*/true);
if (!Self.IsDerivedFrom(SrcExpr->getBeginLoc(), SrcExpr->getType(),
R->getPointeeType(), Paths))
return TC_NotApplicable;
Self.BuildBasePathArray(Paths, BasePath);
} else
Kind = CK_NoOp;
return TC_Success;
}
/// Tests whether a conversion according to C++ 5.2.9p5 is valid.
TryCastResult
TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType,
bool CStyle, SourceRange OpRange,
unsigned &msg, CastKind &Kind,
CXXCastPath &BasePath) {
// C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be
// cast to type "reference to cv2 D", where D is a class derived from B,
// if a valid standard conversion from "pointer to D" to "pointer to B"
// exists, cv2 >= cv1, and B is not a virtual base class of D.
// In addition, DR54 clarifies that the base must be accessible in the
// current context. Although the wording of DR54 only applies to the pointer
// variant of this rule, the intent is clearly for it to apply to the this
// conversion as well.
const ReferenceType *DestReference = DestType->getAs<ReferenceType>();
if (!DestReference) {
return TC_NotApplicable;
}
bool RValueRef = DestReference->isRValueReferenceType();
if (!RValueRef && !SrcExpr->isLValue()) {
// We know the left side is an lvalue reference, so we can suggest a reason.
msg = diag::err_bad_cxx_cast_rvalue;
return TC_NotApplicable;
}
QualType DestPointee = DestReference->getPointeeType();
// FIXME: If the source is a prvalue, we should issue a warning (because the
// cast always has undefined behavior), and for AST consistency, we should
// materialize a temporary.
return TryStaticDowncast(Self,
Self.Context.getCanonicalType(SrcExpr->getType()),
Self.Context.getCanonicalType(DestPointee), CStyle,
OpRange, SrcExpr->getType(), DestType, msg, Kind,
BasePath);
}
/// Tests whether a conversion according to C++ 5.2.9p8 is valid.
TryCastResult
TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType,
bool CStyle, SourceRange OpRange,
unsigned &msg, CastKind &Kind,
CXXCastPath &BasePath) {
// C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class
// type, can be converted to an rvalue of type "pointer to cv2 D", where D
// is a class derived from B, if a valid standard conversion from "pointer
// to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base
// class of D.
// In addition, DR54 clarifies that the base must be accessible in the
// current context.
const PointerType *DestPointer = DestType->getAs<PointerType>();
if (!DestPointer) {
return TC_NotApplicable;
}
const PointerType *SrcPointer = SrcType->getAs<PointerType>();
if (!SrcPointer) {
msg = diag::err_bad_static_cast_pointer_nonpointer;
return TC_NotApplicable;
}
return TryStaticDowncast(Self,
Self.Context.getCanonicalType(SrcPointer->getPointeeType()),
Self.Context.getCanonicalType(DestPointer->getPointeeType()),
CStyle, OpRange, SrcType, DestType, msg, Kind,
BasePath);
}
/// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and
/// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to
/// DestType is possible and allowed.
TryCastResult
TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType,
bool CStyle, SourceRange OpRange, QualType OrigSrcType,
QualType OrigDestType, unsigned &msg,
CastKind &Kind, CXXCastPath &BasePath) {
// We can only work with complete types. But don't complain if it doesn't work
if (!Self.isCompleteType(OpRange.getBegin(), SrcType) ||
!Self.isCompleteType(OpRange.getBegin(), DestType))
return TC_NotApplicable;
// Downcast can only happen in class hierarchies, so we need classes.
if (!DestType->getAs<RecordType>() || !SrcType->getAs<RecordType>()) {
return TC_NotApplicable;
}
CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
/*DetectVirtual=*/true);
if (!Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths)) {
return TC_NotApplicable;
}
// Target type does derive from source type. Now we're serious. If an error
// appears now, it's not ignored.
// This may not be entirely in line with the standard. Take for example:
// struct A {};
// struct B : virtual A {
// B(A&);
// };
//
// void f()
// {
// (void)static_cast<const B&>(*((A*)0));
// }
// As far as the standard is concerned, p5 does not apply (A is virtual), so
// p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid.
// However, both GCC and Comeau reject this example, and accepting it would
// mean more complex code if we're to preserve the nice error message.
// FIXME: Being 100% compliant here would be nice to have.
// Must preserve cv, as always, unless we're in C-style mode.
if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) {
msg = diag::err_bad_cxx_cast_qualifiers_away;
return TC_Failed;
}
if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) {
// This code is analoguous to that in CheckDerivedToBaseConversion, except
// that it builds the paths in reverse order.
// To sum up: record all paths to the base and build a nice string from
// them. Use it to spice up the error message.
if (!Paths.isRecordingPaths()) {
Paths.clear();
Paths.setRecordingPaths(true);
Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths);
}
std::string PathDisplayStr;
std::set<unsigned> DisplayedPaths;
for (clang::CXXBasePath &Path : Paths) {
if (DisplayedPaths.insert(Path.back().SubobjectNumber).second) {
// We haven't displayed a path to this particular base
// class subobject yet.
PathDisplayStr += "\n ";
for (CXXBasePathElement &PE : llvm::reverse(Path))
PathDisplayStr += PE.Base->getType().getAsString() + " -> ";
PathDisplayStr += QualType(DestType).getAsString();
}
}
Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast)
<< QualType(SrcType).getUnqualifiedType()
<< QualType(DestType).getUnqualifiedType()
<< PathDisplayStr << OpRange;
msg = 0;
return TC_Failed;
}
if (Paths.getDetectedVirtual() != nullptr) {
QualType VirtualBase(Paths.getDetectedVirtual(), 0);
Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual)
<< OrigSrcType << OrigDestType << VirtualBase << OpRange;
msg = 0;
return TC_Failed;
}
if (!CStyle) {
switch (Self.CheckBaseClassAccess(OpRange.getBegin(),
SrcType, DestType,
Paths.front(),
diag::err_downcast_from_inaccessible_base)) {
case Sema::AR_accessible:
case Sema::AR_delayed: // be optimistic
case Sema::AR_dependent: // be optimistic
break;
case Sema::AR_inaccessible:
msg = 0;
return TC_Failed;
}
}
Self.BuildBasePathArray(Paths, BasePath);
Kind = CK_BaseToDerived;
return TC_Success;
}
/// TryStaticMemberPointerUpcast - Tests whether a conversion according to
/// C++ 5.2.9p9 is valid:
///
/// An rvalue of type "pointer to member of D of type cv1 T" can be
/// converted to an rvalue of type "pointer to member of B of type cv2 T",
/// where B is a base class of D [...].
///
TryCastResult
TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType,
QualType DestType, bool CStyle,
SourceRange OpRange,
unsigned &msg, CastKind &Kind,
CXXCastPath &BasePath) {
const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>();
if (!DestMemPtr)
return TC_NotApplicable;
bool WasOverloadedFunction = false;
DeclAccessPair FoundOverload;
if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
if (FunctionDecl *Fn
= Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, false,
FoundOverload)) {
CXXMethodDecl *M = cast<CXXMethodDecl>(Fn);
SrcType = Self.Context.getMemberPointerType(Fn->getType(),
Self.Context.getTypeDeclType(M->getParent()).getTypePtr());
WasOverloadedFunction = true;
}
}
const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>();
if (!SrcMemPtr) {
msg = diag::err_bad_static_cast_member_pointer_nonmp;
return TC_NotApplicable;
}
// Lock down the inheritance model right now in MS ABI, whether or not the
// pointee types are the same.
if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) {
(void)Self.isCompleteType(OpRange.getBegin(), SrcType);
(void)Self.isCompleteType(OpRange.getBegin(), DestType);
}
// T == T, modulo cv
if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(),
DestMemPtr->getPointeeType()))
return TC_NotApplicable;
// B base of D
QualType SrcClass(SrcMemPtr->getClass(), 0);
QualType DestClass(DestMemPtr->getClass(), 0);
CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
/*DetectVirtual=*/true);
if (!Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths))
return TC_NotApplicable;
// B is a base of D. But is it an allowed base? If not, it's a hard error.
if (Paths.isAmbiguous(Self.Context.getCanonicalType(DestClass))) {
Paths.clear();
Paths.setRecordingPaths(true);
bool StillOkay =
Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths);
assert(StillOkay);
(void)StillOkay;
std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths);
Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv)
<< 1 << SrcClass << DestClass << PathDisplayStr << OpRange;
msg = 0;
return TC_Failed;
}
if (const RecordType *VBase = Paths.getDetectedVirtual()) {
Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual)
<< SrcClass << DestClass << QualType(VBase, 0) << OpRange;
msg = 0;
return TC_Failed;
}
if (!CStyle) {
switch (Self.CheckBaseClassAccess(OpRange.getBegin(),
DestClass, SrcClass,
Paths.front(),
diag::err_upcast_to_inaccessible_base)) {
case Sema::AR_accessible:
case Sema::AR_delayed:
case Sema::AR_dependent:
// Optimistically assume that the delayed and dependent cases
// will work out.
break;
case Sema::AR_inaccessible:
msg = 0;
return TC_Failed;
}
}
if (WasOverloadedFunction) {
// Resolve the address of the overloaded function again, this time
// allowing complaints if something goes wrong.
FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(),
DestType,
true,
FoundOverload);
if (!Fn) {
msg = 0;
return TC_Failed;
}
SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr, FoundOverload, Fn);
if (!SrcExpr.isUsable()) {
msg = 0;
return TC_Failed;
}
}
Self.BuildBasePathArray(Paths, BasePath);
Kind = CK_DerivedToBaseMemberPointer;
return TC_Success;
}
/// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2
/// is valid:
///
/// An expression e can be explicitly converted to a type T using a
/// @c static_cast if the declaration "T t(e);" is well-formed [...].
TryCastResult
TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType,
Sema::CheckedConversionKind CCK,
SourceRange OpRange, unsigned &msg,
CastKind &Kind, bool ListInitialization) {
if (DestType->isRecordType()) {
if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
diag::err_bad_dynamic_cast_incomplete) ||
Self.RequireNonAbstractType(OpRange.getBegin(), DestType,
diag::err_allocation_of_abstract_type)) {
msg = 0;
return TC_Failed;
}
}
InitializedEntity Entity = InitializedEntity::InitializeTemporary(DestType);
InitializationKind InitKind
= (CCK == Sema::CCK_CStyleCast)
? InitializationKind::CreateCStyleCast(OpRange.getBegin(), OpRange,
ListInitialization)
: (CCK == Sema::CCK_FunctionalCast)
? InitializationKind::CreateFunctionalCast(OpRange, ListInitialization)
: InitializationKind::CreateCast(OpRange);
Expr *SrcExprRaw = SrcExpr.get();
// FIXME: Per DR242, we should check for an implicit conversion sequence
// or for a constructor that could be invoked by direct-initialization
// here, not for an initialization sequence.
InitializationSequence InitSeq(Self, Entity, InitKind, SrcExprRaw);
// At this point of CheckStaticCast, if the destination is a reference,
// or the expression is an overload expression this has to work.
// There is no other way that works.
// On the other hand, if we're checking a C-style cast, we've still got
// the reinterpret_cast way.
bool CStyle
= (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast);
if (InitSeq.Failed() && (CStyle || !DestType->isReferenceType()))
return TC_NotApplicable;
ExprResult Result = InitSeq.Perform(Self, Entity, InitKind, SrcExprRaw);
if (Result.isInvalid()) {
msg = 0;
return TC_Failed;
}
if (InitSeq.isConstructorInitialization())
Kind = CK_ConstructorConversion;
else
Kind = CK_NoOp;
SrcExpr = Result;
return TC_Success;
}
/// TryConstCast - See if a const_cast from source to destination is allowed,
/// and perform it if it is.
static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr,
QualType DestType, bool CStyle,
unsigned &msg) {
DestType = Self.Context.getCanonicalType(DestType);
QualType SrcType = SrcExpr.get()->getType();
bool NeedToMaterializeTemporary = false;
if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) {
// C++11 5.2.11p4:
// if a pointer to T1 can be explicitly converted to the type "pointer to
// T2" using a const_cast, then the following conversions can also be
// made:
// -- an lvalue of type T1 can be explicitly converted to an lvalue of
// type T2 using the cast const_cast<T2&>;
// -- a glvalue of type T1 can be explicitly converted to an xvalue of
// type T2 using the cast const_cast<T2&&>; and
// -- if T1 is a class type, a prvalue of type T1 can be explicitly
// converted to an xvalue of type T2 using the cast const_cast<T2&&>.
if (isa<LValueReferenceType>(DestTypeTmp) && !SrcExpr.get()->isLValue()) {
// Cannot const_cast non-lvalue to lvalue reference type. But if this
// is C-style, static_cast might find a way, so we simply suggest a
// message and tell the parent to keep searching.
msg = diag::err_bad_cxx_cast_rvalue;
return TC_NotApplicable;
}
if (isa<RValueReferenceType>(DestTypeTmp) && SrcExpr.get()->isRValue()) {
if (!SrcType->isRecordType()) {
// Cannot const_cast non-class prvalue to rvalue reference type. But if
// this is C-style, static_cast can do this.
msg = diag::err_bad_cxx_cast_rvalue;
return TC_NotApplicable;
}
// Materialize the class prvalue so that the const_cast can bind a
// reference to it.
NeedToMaterializeTemporary = true;
}
// It's not completely clear under the standard whether we can
// const_cast bit-field gl-values. Doing so would not be
// intrinsically complicated, but for now, we say no for
// consistency with other compilers and await the word of the
// committee.
if (SrcExpr.get()->refersToBitField()) {
msg = diag::err_bad_cxx_cast_bitfield;
return TC_NotApplicable;
}
DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
SrcType = Self.Context.getPointerType(SrcType);
}
// C++ 5.2.11p5: For a const_cast involving pointers to data members [...]
// the rules for const_cast are the same as those used for pointers.
if (!DestType->isPointerType() &&
!DestType->isMemberPointerType() &&
!DestType->isObjCObjectPointerType()) {
// Cannot cast to non-pointer, non-reference type. Note that, if DestType
// was a reference type, we converted it to a pointer above.
// The status of rvalue references isn't entirely clear, but it looks like
// conversion to them is simply invalid.
// C++ 5.2.11p3: For two pointer types [...]
if (!CStyle)
msg = diag::err_bad_const_cast_dest;
return TC_NotApplicable;
}
if (DestType->isFunctionPointerType() ||
DestType->isMemberFunctionPointerType()) {
// Cannot cast direct function pointers.
// C++ 5.2.11p2: [...] where T is any object type or the void type [...]
// T is the ultimate pointee of source and target type.
if (!CStyle)
msg = diag::err_bad_const_cast_dest;
return TC_NotApplicable;
}
// C++ [expr.const.cast]p3:
// "For two similar types T1 and T2, [...]"
//
// We only allow a const_cast to change cvr-qualifiers, not other kinds of
// type qualifiers. (Likewise, we ignore other changes when determining
// whether a cast casts away constness.)
if (!Self.Context.hasCvrSimilarType(SrcType, DestType))
return TC_NotApplicable;
if (NeedToMaterializeTemporary)
// This is a const_cast from a class prvalue to an rvalue reference type.
// Materialize a temporary to store the result of the conversion.
SrcExpr = Self.CreateMaterializeTemporaryExpr(SrcExpr.get()->getType(),
SrcExpr.get(),
/*IsLValueReference*/ false);
return TC_Success;
}
// Checks for undefined behavior in reinterpret_cast.
// The cases that is checked for is:
// *reinterpret_cast<T*>(&a)
// reinterpret_cast<T&>(a)
// where accessing 'a' as type 'T' will result in undefined behavior.
void Sema::CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType,
bool IsDereference,
SourceRange Range) {
unsigned DiagID = IsDereference ?
diag::warn_pointer_indirection_from_incompatible_type :
diag::warn_undefined_reinterpret_cast;
if (Diags.isIgnored(DiagID, Range.getBegin()))
return;
QualType SrcTy, DestTy;
if (IsDereference) {
if (!SrcType->getAs<PointerType>() || !DestType->getAs<PointerType>()) {
return;
}
SrcTy = SrcType->getPointeeType();
DestTy = DestType->getPointeeType();
} else {
if (!DestType->getAs<ReferenceType>()) {
return;
}
SrcTy = SrcType;
DestTy = DestType->getPointeeType();
}
// Cast is compatible if the types are the same.
if (Context.hasSameUnqualifiedType(DestTy, SrcTy)) {
return;
}
// or one of the types is a char or void type
if (DestTy->isAnyCharacterType() || DestTy->isVoidType() ||
SrcTy->isAnyCharacterType() || SrcTy->isVoidType()) {
return;
}
// or one of the types is a tag type.
if (SrcTy->getAs<TagType>() || DestTy->getAs<TagType>()) {
return;
}
// FIXME: Scoped enums?
if ((SrcTy->isUnsignedIntegerType() && DestTy->isSignedIntegerType()) ||
(SrcTy->isSignedIntegerType() && DestTy->isUnsignedIntegerType())) {
if (Context.getTypeSize(DestTy) == Context.getTypeSize(SrcTy)) {
return;
}
}
Diag(Range.getBegin(), DiagID) << SrcType << DestType << Range;
}
static void DiagnoseCastOfObjCSEL(Sema &Self, const ExprResult &SrcExpr,
QualType DestType) {
QualType SrcType = SrcExpr.get()->getType();
if (Self.Context.hasSameType(SrcType, DestType))
return;
if (const PointerType *SrcPtrTy = SrcType->getAs<PointerType>())
if (SrcPtrTy->isObjCSelType()) {
QualType DT = DestType;
if (isa<PointerType>(DestType))
DT = DestType->getPointeeType();
if (!DT.getUnqualifiedType()->isVoidType())
Self.Diag(SrcExpr.get()->getExprLoc(),
diag::warn_cast_pointer_from_sel)
<< SrcType << DestType << SrcExpr.get()->getSourceRange();
}
}
/// Diagnose casts that change the calling convention of a pointer to a function
/// defined in the current TU.
static void DiagnoseCallingConvCast(Sema &Self, const ExprResult &SrcExpr,
QualType DstType, SourceRange OpRange) {
// Check if this cast would change the calling convention of a function
// pointer type.
QualType SrcType = SrcExpr.get()->getType();
if (Self.Context.hasSameType(SrcType, DstType) ||
!SrcType->isFunctionPointerType() || !DstType->isFunctionPointerType())
return;
const auto *SrcFTy =
SrcType->castAs<PointerType>()->getPointeeType()->castAs<FunctionType>();
const auto *DstFTy =
DstType->castAs<PointerType>()->getPointeeType()->castAs<FunctionType>();
CallingConv SrcCC = SrcFTy->getCallConv();
CallingConv DstCC = DstFTy->getCallConv();
if (SrcCC == DstCC)
return;
// We have a calling convention cast. Check if the source is a pointer to a
// known, specific function that has already been defined.
Expr *Src = SrcExpr.get()->IgnoreParenImpCasts();
if (auto *UO = dyn_cast<UnaryOperator>(Src))
if (UO->getOpcode() == UO_AddrOf)
Src = UO->getSubExpr()->IgnoreParenImpCasts();
auto *DRE = dyn_cast<DeclRefExpr>(Src);
if (!DRE)
return;
auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl());
if (!FD)
return;
// Only warn if we are casting from the default convention to a non-default
// convention. This can happen when the programmer forgot to apply the calling
// convention to the function declaration and then inserted this cast to
// satisfy the type system.
CallingConv DefaultCC = Self.getASTContext().getDefaultCallingConvention(
FD->isVariadic(), FD->isCXXInstanceMember());
if (DstCC == DefaultCC || SrcCC != DefaultCC)
return;
// Diagnose this cast, as it is probably bad.
StringRef SrcCCName = FunctionType::getNameForCallConv(SrcCC);
StringRef DstCCName = FunctionType::getNameForCallConv(DstCC);
Self.Diag(OpRange.getBegin(), diag::warn_cast_calling_conv)
<< SrcCCName << DstCCName << OpRange;
// The checks above are cheaper than checking if the diagnostic is enabled.
// However, it's worth checking if the warning is enabled before we construct
// a fixit.
if (Self.Diags.isIgnored(diag::warn_cast_calling_conv, OpRange.getBegin()))
return;
// Try to suggest a fixit to change the calling convention of the function
// whose address was taken. Try to use the latest macro for the convention.
// For example, users probably want to write "WINAPI" instead of "__stdcall"
// to match the Windows header declarations.
SourceLocation NameLoc = FD->getFirstDecl()->getNameInfo().getLoc();
Preprocessor &PP = Self.getPreprocessor();
SmallVector<TokenValue, 6> AttrTokens;
SmallString<64> CCAttrText;
llvm::raw_svector_ostream OS(CCAttrText);
if (Self.getLangOpts().MicrosoftExt) {
// __stdcall or __vectorcall
OS << "__" << DstCCName;
IdentifierInfo *II = PP.getIdentifierInfo(OS.str());
AttrTokens.push_back(II->isKeyword(Self.getLangOpts())
? TokenValue(II->getTokenID())
: TokenValue(II));
} else {
// __attribute__((stdcall)) or __attribute__((vectorcall))
OS << "__attribute__((" << DstCCName << "))";
AttrTokens.push_back(tok::kw___attribute);
AttrTokens.push_back(tok::l_paren);
AttrTokens.push_back(tok::l_paren);
IdentifierInfo *II = PP.getIdentifierInfo(DstCCName);
AttrTokens.push_back(II->isKeyword(Self.getLangOpts())
? TokenValue(II->getTokenID())
: TokenValue(II));
AttrTokens.push_back(tok::r_paren);
AttrTokens.push_back(tok::r_paren);
}
StringRef AttrSpelling = PP.getLastMacroWithSpelling(NameLoc, AttrTokens);
if (!AttrSpelling.empty())
CCAttrText = AttrSpelling;
OS << ' ';
Self.Diag(NameLoc, diag::note_change_calling_conv_fixit)
<< FD << DstCCName << FixItHint::CreateInsertion(NameLoc, CCAttrText);
}
static void checkIntToPointerCast(bool CStyle, SourceLocation Loc,
const Expr *SrcExpr, QualType DestType,
Sema &Self) {
QualType SrcType = SrcExpr->getType();
// Not warning on reinterpret_cast, boolean, constant expressions, etc
// are not explicit design choices, but consistent with GCC's behavior.
// Feel free to modify them if you've reason/evidence for an alternative.
if (CStyle && SrcType->isIntegralType(Self.Context)
&& !SrcType->isBooleanType()
&& !SrcType->isEnumeralType()
&& !SrcExpr->isIntegerConstantExpr(Self.Context)
&& Self.Context.getTypeSize(DestType) >
Self.Context.getTypeSize(SrcType)) {
// Separate between casts to void* and non-void* pointers.
// Some APIs use (abuse) void* for something like a user context,
// and often that value is an integer even if it isn't a pointer itself.
// Having a separate warning flag allows users to control the warning
// for their workflow.
unsigned Diag = DestType->isVoidPointerType() ?
diag::warn_int_to_void_pointer_cast
: diag::warn_int_to_pointer_cast;
Self.Diag(Loc, Diag) << SrcType << DestType;
}
}
static bool fixOverloadedReinterpretCastExpr(Sema &Self, QualType DestType,
ExprResult &Result) {
// We can only fix an overloaded reinterpret_cast if
// - it is a template with explicit arguments that resolves to an lvalue
// unambiguously, or
// - it is the only function in an overload set that may have its address
// taken.
Expr *E = Result.get();
// TODO: what if this fails because of DiagnoseUseOfDecl or something
// like it?
if (Self.ResolveAndFixSingleFunctionTemplateSpecialization(
Result,
Expr::getValueKindForType(DestType) == VK_RValue // Convert Fun to Ptr
) &&
Result.isUsable())
return true;
// No guarantees that ResolveAndFixSingleFunctionTemplateSpecialization
// preserves Result.
Result = E;
if (!Self.resolveAndFixAddressOfOnlyViableOverloadCandidate(
Result, /*DoFunctionPointerConversion=*/true))
return false;
return Result.isUsable();
}
static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
QualType DestType, bool CStyle,
SourceRange OpRange,
unsigned &msg,
CastKind &Kind) {
bool IsLValueCast = false;
DestType = Self.Context.getCanonicalType(DestType);
QualType SrcType = SrcExpr.get()->getType();
// Is the source an overloaded name? (i.e. &foo)
// If so, reinterpret_cast generally can not help us here (13.4, p1, bullet 5)
if (SrcType == Self.Context.OverloadTy) {
ExprResult FixedExpr = SrcExpr;
if (!fixOverloadedReinterpretCastExpr(Self, DestType, FixedExpr))
return TC_NotApplicable;
assert(FixedExpr.isUsable() && "Invalid result fixing overloaded expr");
SrcExpr = FixedExpr;
SrcType = SrcExpr.get()->getType();
}
if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) {
if (!SrcExpr.get()->isGLValue()) {
// Cannot cast non-glvalue to (lvalue or rvalue) reference type. See the
// similar comment in const_cast.
msg = diag::err_bad_cxx_cast_rvalue;
return TC_NotApplicable;
}
if (!CStyle) {
Self.CheckCompatibleReinterpretCast(SrcType, DestType,
/*isDereference=*/false, OpRange);
}
// C++ 5.2.10p10: [...] a reference cast reinterpret_cast<T&>(x) has the
// same effect as the conversion *reinterpret_cast<T*>(&x) with the
// built-in & and * operators.
const char *inappropriate = nullptr;
switch (SrcExpr.get()->getObjectKind()) {
case OK_Ordinary:
break;
case OK_BitField:
msg = diag::err_bad_cxx_cast_bitfield;
return TC_NotApplicable;
// FIXME: Use a specific diagnostic for the rest of these cases.
case OK_VectorComponent: inappropriate = "vector element"; break;
case OK_ObjCProperty: inappropriate = "property expression"; break;
case OK_ObjCSubscript: inappropriate = "container subscripting expression";
break;
}
if (inappropriate) {
Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference)
<< inappropriate << DestType
<< OpRange << SrcExpr.get()->getSourceRange();
msg = 0; SrcExpr = ExprError();
return TC_NotApplicable;
}
// This code does this transformation for the checked types.
DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
SrcType = Self.Context.getPointerType(SrcType);
IsLValueCast = true;
}
// Canonicalize source for comparison.
SrcType = Self.Context.getCanonicalType(SrcType);
const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(),
*SrcMemPtr = SrcType->getAs<MemberPointerType>();
if (DestMemPtr && SrcMemPtr) {
// C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1"
// can be explicitly converted to an rvalue of type "pointer to member
// of Y of type T2" if T1 and T2 are both function types or both object
// types.
if (DestMemPtr->isMemberFunctionPointer() !=
SrcMemPtr->isMemberFunctionPointer())
return TC_NotApplicable;
if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) {
// We need to determine the inheritance model that the class will use if
// haven't yet.
(void)Self.isCompleteType(OpRange.getBegin(), SrcType);
(void)Self.isCompleteType(OpRange.getBegin(), DestType);
}
// Don't allow casting between member pointers of different sizes.
if (Self.Context.getTypeSize(DestMemPtr) !=
Self.Context.getTypeSize(SrcMemPtr)) {
msg = diag::err_bad_cxx_cast_member_pointer_size;
return TC_Failed;
}
// C++ 5.2.10p2: The reinterpret_cast operator shall not cast away
// constness.
// A reinterpret_cast followed by a const_cast can, though, so in C-style,
// we accept it.
if (auto CACK =
CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle,
/*CheckObjCLifetime=*/CStyle))
return getCastAwayConstnessCastKind(CACK, msg);
// A valid member pointer cast.
assert(!IsLValueCast);
Kind = CK_ReinterpretMemberPointer;
return TC_Success;
}
// See below for the enumeral issue.
if (SrcType->isNullPtrType() && DestType->isIntegralType(Self.Context)) {
// C++0x 5.2.10p4: A pointer can be explicitly converted to any integral
// type large enough to hold it. A value of std::nullptr_t can be
// converted to an integral type; the conversion has the same meaning
// and validity as a conversion of (void*)0 to the integral type.
if (Self.Context.getTypeSize(SrcType) >
Self.Context.getTypeSize(DestType)) {
msg = diag::err_bad_reinterpret_cast_small_int;
return TC_Failed;
}
Kind = CK_PointerToIntegral;
return TC_Success;
}
// Allow reinterpret_casts between vectors of the same size and
// between vectors and integers of the same size.
bool destIsVector = DestType->isVectorType();
bool srcIsVector = SrcType->isVectorType();
if (srcIsVector || destIsVector) {
// The non-vector type, if any, must have integral type. This is
// the same rule that C vector casts use; note, however, that enum
// types are not integral in C++.
if ((!destIsVector && !DestType->isIntegralType(Self.Context)) ||
(!srcIsVector && !SrcType->isIntegralType(Self.Context)))
return TC_NotApplicable;
// The size we want to consider is eltCount * eltSize.
// That's exactly what the lax-conversion rules will check.
if (Self.areLaxCompatibleVectorTypes(SrcType, DestType)) {
Kind = CK_BitCast;
return TC_Success;
}
// Otherwise, pick a reasonable diagnostic.
if (!destIsVector)
msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size;
else if (!srcIsVector)
msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size;
else
msg = diag::err_bad_cxx_cast_vector_to_vector_different_size;
return TC_Failed;
}
if (SrcType == DestType) {
// C++ 5.2.10p2 has a note that mentions that, subject to all other
// restrictions, a cast to the same type is allowed so long as it does not
// cast away constness. In C++98, the intent was not entirely clear here,
// since all other paragraphs explicitly forbid casts to the same type.
// C++11 clarifies this case with p2.
//
// The only allowed types are: integral, enumeration, pointer, or
// pointer-to-member types. We also won't restrict Obj-C pointers either.
Kind = CK_NoOp;
TryCastResult Result = TC_NotApplicable;
if (SrcType->isIntegralOrEnumerationType() ||
SrcType->isAnyPointerType() ||
SrcType->isMemberPointerType() ||
SrcType->isBlockPointerType()) {
Result = TC_Success;
}
return Result;
}
bool destIsPtr = DestType->isAnyPointerType() ||
DestType->isBlockPointerType();
bool srcIsPtr = SrcType->isAnyPointerType() ||
SrcType->isBlockPointerType();
if (!destIsPtr && !srcIsPtr) {
// Except for std::nullptr_t->integer and lvalue->reference, which are
// handled above, at least one of the two arguments must be a pointer.
return TC_NotApplicable;
}
if (DestType->isIntegralType(Self.Context)) {
assert(srcIsPtr && "One type must be a pointer");
// C++ 5.2.10p4: A pointer can be explicitly converted to any integral
// type large enough to hold it; except in Microsoft mode, where the
// integral type size doesn't matter (except we don't allow bool).
bool MicrosoftException = Self.getLangOpts().MicrosoftExt &&
!DestType->isBooleanType();
if ((Self.Context.getTypeSize(SrcType) >
Self.Context.getTypeSize(DestType)) &&
!MicrosoftException) {
msg = diag::err_bad_reinterpret_cast_small_int;
return TC_Failed;
}
Kind = CK_PointerToIntegral;
return TC_Success;
}
if (SrcType->isIntegralOrEnumerationType()) {
assert(destIsPtr && "One type must be a pointer");
checkIntToPointerCast(CStyle, OpRange.getBegin(), SrcExpr.get(), DestType,
Self);
// C++ 5.2.10p5: A value of integral or enumeration type can be explicitly
// converted to a pointer.
// C++ 5.2.10p9: [Note: ...a null pointer constant of integral type is not
// necessarily converted to a null pointer value.]
Kind = CK_IntegralToPointer;
return TC_Success;
}
if (!destIsPtr || !srcIsPtr) {
// With the valid non-pointer conversions out of the way, we can be even
// more stringent.
return TC_NotApplicable;
}
// Cannot convert between block pointers and Objective-C object pointers.
if ((SrcType->isBlockPointerType() && DestType->isObjCObjectPointerType()) ||
(DestType->isBlockPointerType() && SrcType->isObjCObjectPointerType()))
return TC_NotApplicable;
// C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness.
// The C-style cast operator can.
TryCastResult SuccessResult = TC_Success;
if (auto CACK =
CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle,
/*CheckObjCLifetime=*/CStyle))
SuccessResult = getCastAwayConstnessCastKind(CACK, msg);
if (IsAddressSpaceConversion(SrcType, DestType)) {
Kind = CK_AddressSpaceConversion;
assert(SrcType->isPointerType() && DestType->isPointerType());
if (!CStyle &&
!DestType->getPointeeType().getQualifiers().isAddressSpaceSupersetOf(
SrcType->getPointeeType().getQualifiers())) {
SuccessResult = TC_Failed;
}
} else if (IsLValueCast) {
Kind = CK_LValueBitCast;
} else if (DestType->isObjCObjectPointerType()) {
Kind = Self.PrepareCastToObjCObjectPointer(SrcExpr);
} else if (DestType->isBlockPointerType()) {
if (!SrcType->isBlockPointerType()) {
Kind = CK_AnyPointerToBlockPointerCast;
} else {
Kind = CK_BitCast;
}
} else {
Kind = CK_BitCast;
}
// Any pointer can be cast to an Objective-C pointer type with a C-style
// cast.
if (CStyle && DestType->isObjCObjectPointerType()) {
return SuccessResult;
}
if (CStyle)
DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType);
DiagnoseCallingConvCast(Self, SrcExpr, DestType, OpRange);
// Not casting away constness, so the only remaining check is for compatible
// pointer categories.
if (SrcType->isFunctionPointerType()) {
if (DestType->isFunctionPointerType()) {
// C++ 5.2.10p6: A pointer to a function can be explicitly converted to
// a pointer to a function of a different type.
return SuccessResult;
}
// C++0x 5.2.10p8: Converting a pointer to a function into a pointer to
// an object type or vice versa is conditionally-supported.
// Compilers support it in C++03 too, though, because it's necessary for
// casting the return value of dlsym() and GetProcAddress().
// FIXME: Conditionally-supported behavior should be configurable in the
// TargetInfo or similar.
Self.Diag(OpRange.getBegin(),
Self.getLangOpts().CPlusPlus11 ?
diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj)
<< OpRange;
return SuccessResult;
}
if (DestType->isFunctionPointerType()) {
// See above.
Self.Diag(OpRange.getBegin(),
Self.getLangOpts().CPlusPlus11 ?
diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj)
<< OpRange;
return SuccessResult;
}
// C++ 5.2.10p7: A pointer to an object can be explicitly converted to
// a pointer to an object of different type.
// Void pointers are not specified, but supported by every compiler out there.
// So we finish by allowing everything that remains - it's got to be two
// object pointers.
return SuccessResult;
}
static TryCastResult TryAddressSpaceCast(Sema &Self, ExprResult &SrcExpr,
QualType DestType, bool CStyle,
unsigned &msg) {
if (!Self.getLangOpts().OpenCL)
// FIXME: As compiler doesn't have any information about overlapping addr
// spaces at the moment we have to be permissive here.
return TC_NotApplicable;
// Even though the logic below is general enough and can be applied to
// non-OpenCL mode too, we fast-path above because no other languages
// define overlapping address spaces currently.
auto SrcType = SrcExpr.get()->getType();
auto SrcPtrType = SrcType->getAs<PointerType>();
if (!SrcPtrType)
return TC_NotApplicable;
auto DestPtrType = DestType->getAs<PointerType>();
if (!DestPtrType)
return TC_NotApplicable;
auto SrcPointeeType = SrcPtrType->getPointeeType();
auto DestPointeeType = DestPtrType->getPointeeType();
if (SrcPointeeType.getAddressSpace() == DestPointeeType.getAddressSpace())
return TC_NotApplicable;
if (!DestPtrType->isAddressSpaceOverlapping(*SrcPtrType)) {
msg = diag::err_bad_cxx_cast_addr_space_mismatch;
return TC_Failed;
}
auto SrcPointeeTypeWithoutAS =
Self.Context.removeAddrSpaceQualType(SrcPointeeType.getCanonicalType());
auto DestPointeeTypeWithoutAS =
Self.Context.removeAddrSpaceQualType(DestPointeeType.getCanonicalType());
return Self.Context.hasSameType(SrcPointeeTypeWithoutAS,
DestPointeeTypeWithoutAS)
? TC_Success
: TC_NotApplicable;
}
void CastOperation::checkAddressSpaceCast(QualType SrcType, QualType DestType) {
// In OpenCL only conversions between pointers to objects in overlapping
// addr spaces are allowed. v2.0 s6.5.5 - Generic addr space overlaps
// with any named one, except for constant.
// Converting the top level pointee addrspace is permitted for compatible
// addrspaces (such as 'generic int *' to 'local int *' or vice versa), but
// if any of the nested pointee addrspaces differ, we emit a warning
// regardless of addrspace compatibility. This makes
// local int ** p;
// return (generic int **) p;
// warn even though local -> generic is permitted.
if (Self.getLangOpts().OpenCL) {
const Type *DestPtr, *SrcPtr;
bool Nested = false;
unsigned DiagID = diag::err_typecheck_incompatible_address_space;
DestPtr = Self.getASTContext().getCanonicalType(DestType.getTypePtr()),
SrcPtr = Self.getASTContext().getCanonicalType(SrcType.getTypePtr());
while (isa<PointerType>(DestPtr) && isa<PointerType>(SrcPtr)) {
const PointerType *DestPPtr = cast<PointerType>(DestPtr);
const PointerType *SrcPPtr = cast<PointerType>(SrcPtr);
QualType DestPPointee = DestPPtr->getPointeeType();
QualType SrcPPointee = SrcPPtr->getPointeeType();
if (Nested ? DestPPointee.getAddressSpace() !=
SrcPPointee.getAddressSpace()
: !DestPPtr->isAddressSpaceOverlapping(*SrcPPtr)) {
Self.Diag(OpRange.getBegin(), DiagID)
<< SrcType << DestType << Sema::AA_Casting
<< SrcExpr.get()->getSourceRange();
if (!Nested)
SrcExpr = ExprError();
return;
}
DestPtr = DestPPtr->getPointeeType().getTypePtr();
SrcPtr = SrcPPtr->getPointeeType().getTypePtr();
Nested = true;
DiagID = diag::ext_nested_pointer_qualifier_mismatch;
}
}
}
void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle,
bool ListInitialization) {
assert(Self.getLangOpts().CPlusPlus);
// Handle placeholders.
if (isPlaceholder()) {
// C-style casts can resolve __unknown_any types.
if (claimPlaceholder(BuiltinType::UnknownAny)) {
SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType,
SrcExpr.get(), Kind,
ValueKind, BasePath);
return;
}
checkNonOverloadPlaceholders();
if (SrcExpr.isInvalid())
return;
}
// C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
// This test is outside everything else because it's the only case where
// a non-lvalue-reference target type does not lead to decay.
if (DestType->isVoidType()) {
Kind = CK_ToVoid;
if (claimPlaceholder(BuiltinType::Overload)) {
Self.ResolveAndFixSingleFunctionTemplateSpecialization(
SrcExpr, /* Decay Function to ptr */ false,
/* Complain */ true, DestRange, DestType,
diag::err_bad_cstyle_cast_overload);
if (SrcExpr.isInvalid())
return;
}
SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
return;
}
// If the type is dependent, we won't do any other semantic analysis now.
if (DestType->isDependentType() || SrcExpr.get()->isTypeDependent() ||
SrcExpr.get()->isValueDependent()) {
assert(Kind == CK_Dependent);
return;
}
if (ValueKind == VK_RValue && !DestType->isRecordType() &&
!isPlaceholder(BuiltinType::Overload)) {
SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
if (SrcExpr.isInvalid())
return;
}
// AltiVec vector initialization with a single literal.
if (const VectorType *vecTy = DestType->getAs<VectorType>())
if (vecTy->getVectorKind() == VectorType::AltiVecVector
&& (SrcExpr.get()->getType()->isIntegerType()
|| SrcExpr.get()->getType()->isFloatingType())) {
Kind = CK_VectorSplat;
SrcExpr = Self.prepareVectorSplat(DestType, SrcExpr.get());
return;
}
// C++ [expr.cast]p5: The conversions performed by
// - a const_cast,
// - a static_cast,
// - a static_cast followed by a const_cast,
// - a reinterpret_cast, or
// - a reinterpret_cast followed by a const_cast,
// can be performed using the cast notation of explicit type conversion.
// [...] If a conversion can be interpreted in more than one of the ways
// listed above, the interpretation that appears first in the list is used,
// even if a cast resulting from that interpretation is ill-formed.
// In plain language, this means trying a const_cast ...
// Note that for address space we check compatibility after const_cast.
unsigned msg = diag::err_bad_cxx_cast_generic;
TryCastResult tcr = TryConstCast(Self, SrcExpr, DestType,
/*CStyle*/ true, msg);
if (SrcExpr.isInvalid())
return;
if (isValidCast(tcr))
Kind = CK_NoOp;
Sema::CheckedConversionKind CCK =
FunctionalStyle ? Sema::CCK_FunctionalCast : Sema::CCK_CStyleCast;
if (tcr == TC_NotApplicable) {
tcr = TryAddressSpaceCast(Self, SrcExpr, DestType, /*CStyle*/ true, msg);
if (SrcExpr.isInvalid())
return;
if (tcr == TC_NotApplicable) {
// ... or if that is not possible, a static_cast, ignoring const, ...
tcr = TryStaticCast(Self, SrcExpr, DestType, CCK, OpRange, msg, Kind,
BasePath, ListInitialization);
if (SrcExpr.isInvalid())
return;
if (tcr == TC_NotApplicable) {
// ... and finally a reinterpret_cast, ignoring const.
tcr = TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/ true,
OpRange, msg, Kind);
if (SrcExpr.isInvalid())
return;
}
}
}
if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() &&
isValidCast(tcr))
checkObjCConversion(CCK);
if (tcr != TC_Success && msg != 0) {
if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
DeclAccessPair Found;
FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(),
DestType,
/*Complain*/ true,
Found);
if (Fn) {
// If DestType is a function type (not to be confused with the function
// pointer type), it will be possible to resolve the function address,
// but the type cast should be considered as failure.
OverloadExpr *OE = OverloadExpr::find(SrcExpr.get()).Expression;
Self.Diag(OpRange.getBegin(), diag::err_bad_cstyle_cast_overload)
<< OE->getName() << DestType << OpRange
<< OE->getQualifierLoc().getSourceRange();
Self.NoteAllOverloadCandidates(SrcExpr.get());
}
} else {
diagnoseBadCast(Self, msg, (FunctionalStyle ? CT_Functional : CT_CStyle),
OpRange, SrcExpr.get(), DestType, ListInitialization);
}
}
if (isValidCast(tcr)) {
if (Kind == CK_BitCast)
checkCastAlign();
} else {
SrcExpr = ExprError();
}
}
/// DiagnoseBadFunctionCast - Warn whenever a function call is cast to a
/// non-matching type. Such as enum function call to int, int call to
/// pointer; etc. Cast to 'void' is an exception.
static void DiagnoseBadFunctionCast(Sema &Self, const ExprResult &SrcExpr,
QualType DestType) {
if (Self.Diags.isIgnored(diag::warn_bad_function_cast,
SrcExpr.get()->getExprLoc()))
return;